 |
| Sipadantonius roihani Boonyanusith, Wongkamhaeng & Azman, 2024 |
Abstract
A new genus and species of the family Pseudocyclopidae, Sipadantonius roihani gen. et sp. nov., was described based on specimens collected using a light trap in the marine cave of Sipadan Island, Sabah, Malaysia. The new genus is most related to Pinkertonius, primarily based on the similarity observed in the armament of ancestral segment IV of the male antennules, the armament of the female P5 Exp-3, the segmentation of the male P5, the armament of the maxillular basal exite, and the relative length of the ancestral segment XXVII of the antennules. Nevertheless, it distinguishes itself from Pinkertonius and all other genera of the family by the absence of the lateral seta of the basis of all swimming legs, the presence of an inner seta on the coxa of the female P5, the reduction of furcal setae I and III, as well as the specific armament of the ancestral segment XX of the antennules and the maxillular coxal endite. The female of Sipadantonius roihani gen. et sp. nov. has aesthetascs on the ancestral segments IV and XX of the antennules, as well as six setae on the maxillular coxal endite, exhibiting the most plesiomorphic characteristics of the family Pseudocyclopidae. The latter characteristic has not been recorded in the order Calanoida. It was hypothesised that the new species was a particle feeder living in the pelagic zone of the marine cave. The existence of the new species supported the assumption that the regional distribution of the family Pseudocyclopidae exhibited the Tethyan track, which might have been the subsequent result of the colonisation of the habitats prior to the closure of the Tethys Sea.
Key words: Crustacea, Southeast Asia, systematics, taxonomy, Zooplankton
 |
| Sipadantonius roihani gen. et sp. nov. female: A habitus, dorsal view B habitus, lateral view C urosome, ventral view D urosome, lateral view E genital double-somite, ventral view F furcal rami, dorsal view G furcal rami, lateral view. Arrowheads indicate integumental pores. Scale bars: 200 μm (A, B); 100 μm (C, D); 50 μm (E−G). |
 |
| Sipadantonius roihani gen. et sp. nov. photographs of lateral surface of basis of swimming legs, female (A−E) and male (F): A posterior hyaline process on basis of P1 (indicated by arrow) B P1 C P3 D P4 E, F P5. Arrowheads indicate cuticular windows on lateral margin of basis. Scale bars: 10 μm. |
Order Calanoida Sars, 1903
Superfamily Pseudocyclopoidea Giesbrecht, 1893
Family Pseudocyclopidae Giesbrecht, 1893
Genus Sipadantonius gen. nov.
Etymology: Named after the type locality, Sipadan Island, Sabah, Malaysia, in combination with the -tonius stem from the existing generic name Pinkertonius Bradford-Grieve, Boxshall & Blanco-Bercial, 2014, alluding to the similarity of the genus Pinkertonius. The gender is masculine.
Sipadantonius roihani sp. nov.
Etymology: The specific epithet was conferred in honour of Mr Roihan Han, a Malaysian deep dive record holder (at a depth of 164 m), who also led the Turtle Tomb exploration activity. Consequently, the name is a noun in the genitive singular.
Chaichat Boonyanusith, Koraon Wongkamhaeng and Abdul-Rahim Azman. 2024. Sipadantonius roihani gen. et sp. nov., A New Genus and Species of Pseudocyclopidae Giesbrecht, 1893 (Copepoda, Calanoida) from the marine cave “Turtle Tomb” of Sipadan Island, Sabah, Malaysia. ZooKeys. 1219: 303-329. DOI: doi.org/10.3897/zookeys.1219.133132
